Electronic equipment generates electric "noise," including, for example, electromagnetic interference (EMI) and radio frequency (RF). In some applications, EMI may be of such a level as to be hazardous to nearby personnel. EMI from electronic equipment can also cause deleterious effects to other electronic equipment. Furthermore, if EMI from an electrical unit reaches a high level, the unit may be judged unsafe by governmental agencies such as the Federal Communications Commission and be required to be recalled and redesigned by the manufacturer.
One attempt to reduce the effects that electrical emanations (such as EMI) have on other electronic equipment is redesigning circuit components. Such redesigning is costly and has limited effects on minimizing electrical emanations.
Another conventional attempt to reduce the effects of electrical emanations includes using a foil shield, placed around the electronic circuitry and connected to ground. Such a shield can reduce in-line metal radiation from electronic circuitry. The foil shield is constructed by adhesively coating an aluminum or cooper foil on both sides of the circuitry and applying an outer wrapping layer of polyester or plastic material thereto. Such aluminum and cooper foil shielding is costly to manufacture and not sufficiently durable.
One conventional attempt to shield electrical emanations in display units has been to place a metal shield between the electrical equipment of the display unit and the display screen. The metal shield is generally a separate piece added at some stage in the manufacturing process. However, having an additional and separate shielding piece is difficult to install and obtain maximum shielding.
Thus there is a need for an apparatus which shields emanations emitted from electronic equipment within a display unit, which is durable and which improves shielding efficiency. Even further, there is a need for a shield which minimizes electrical noise escaping from the display unit without making manufacturing, installation, or assembly difficult or costly.